Why is Willy home? Why is Linda alarmed that he's home?

Answers
2

Willy tells Linda that he is "tired to the death ... and couldn't make it." He claims he "couldn't drive any more. The car kept going off onto to the shoulder." Willy was afraid that he might have an accident. Linda fears he has smashed the car because his return is unusual, especially at this time of night.

Later Willy reveals to Happy that he "got an awful scare. Nearly hit a kid in Yonkers." He has begun not to trust himself behind the wheel of a car, and he shouts at Happy, "The woods are burning! I can't drive a car!" Driving a car is essential to his job as a salesman in New England.

Source(s)

Willy Loman, a sixty-year-old traveling salesman, enters his home late at night with two large sample cases. His wife, Linda, hears him coming up the stairs to their bedroom. She seems worried that something has happened, that he has wrecked the car again, or that he's ill, but Willy assures her that he is fine, just tired.

Sitting on the bed with her, he explains that he came home because he was having trouble staying on the road while he drove, and he is unsure of what caused his distraction. It could've been the coffee he had at a roadside diner or the way he opened the windshield of the car and the scenery and sunshine just washed over him. Whatever it was, it kept taking his mind of the road, and he'd veer onto the shoulder before he knew what was happening. He was so spooked that he drove ten miles an hour all the way home, and now he's tired and grumpy because he's going to miss his morning meeting in Portland, Rhode Island.